1. Field of the Invention
The present invention relates generally to fuel tanks used for flammable or explosive fluids such as gasoline, diesel fuel, and LP-Gas; and more particularly this invention relates to tanks employing thermal distribution to suppress explosion. This invention further relates to improvements in such apparatus for use with lightweight transportable tanks, and more precisely with aluminum tanks, which tend to lose structural integrity under high heat.
2. Description of the Prior Art
In a LP-Gas fuel tank application there is generally provided a metallic tank wall designed to contain the fuel under pressure. This tank is typically of steel composition for stationary applications and further includes associated valves and connections at one end for access to the contents thereof. When the tank is in a heated environment, such as in a fire, the liquid proximate the hot spot will boil and eventually ignite, with a resulting explosion. Prior attempts to neutralize the explosion tendencies of the tank have included providing an expanded aluminum foil mesh as a filler mass insert within the tank. Such a system is described in Canadian Patent No. 736,802. The container is filled with a mesh which divides the container into many small cell-like compartments, and through thermal contact with the mesh the fuel transfers the heat away from the "hot spot" to delay the local rise in temperature--and delay the explosion.
Improvements in tank design have recently been directed to preventing nesting of the mesh insert by reversing alternate layers in a roll. Nesting occurs where the mesh pattern of adjacent layers settle against each other in a mating relation. A recent anti-nesting system is described in U.S. Pat. No. 4,149,649. Even with the anti-nesting technique of the prior art, the lightweight foil of the mesh tended to collapse and compress and its effectiveness diminished during use; this is particularly true for transportable containers, and vehicular fuel tanks. Recently a new technique described in U.S. Pat. No. 4,673,098, issued to Fenton et.al., dramatically improved the thermal conductivity and reduced the compression effect. This method used a thermally conductive adhesive to secure the filler mass within the tank. This kept the filler structure intact and yet facilitated the thermal transfer to the liquid from the adjoining tank surface.
In the vehicle tank industry and in the design of transportable tanks, weight is of high importance and tanks of aluminum composition have been utilitzed. Unfortunately, the aluminum tank wall tends to melt at such a low temperature that its structural integrity is quickly lost in a fire. Attempts to insulate or coat the outer surface of such tanks have proved satisfactory inasmuch as the coating does not remain sufficiently intact to produce reliable results.